Integrated watershed modeling using interval valued fuzzy computations to enhance watershed restoration and protection at field-scale

Abstract

Watershed models are scientific tools required not only for replicating the bio-physicochemical processes occurring on the landscape and water bodies, but also for addressing the complex decision-making process. This involves implementation of sustainable, economically feasible best management practices (BMPs) for watershed restoration and protection. Although numerous watershed models working at different spatio-temporal scales are available, it is often challenging for watershed modelers to identify the best ones which can simultaneously address agronomic, hydrologic, socio-economic and ecological objectives at field scale. Some of the popular models are Better Assessment Science Integrating Point and Nonpoint Sources, SWAT (Soil and Water Assessment Tool), Agriculture Conservation Planning Framework (ACPF), Prioritize Target and Measure Application (PTMApp), etc. In this study, we compare nine contemporary models with primary focus on assessing the ability of these models to achieve agronomic, hydrologic, socio-economic and ecological objectives of a watershed through Best Management Practices (BMPs) adopted at field scale. To achieve these fuzzy objectives, ten suitable criteria such as BMP feasibility, Total Maximum Daily Load scenario assessment, uncertainty analysis, climate change incorporation, cost-effectiveness, field-scale implementation, hydrology replication, stakeholder involvement, etc. have been considered. Modified form of traditional fuzzy computations namely interval-valued fuzzy computations has been used to compare various models based on these criteria. Integrated decision support system (DSS) has been developed that takes into account the subjective and uncertain perceptions of watershed modelers and decision-making bodies using fuzzy logic. Study presents two novel aspects viz. (i) Usage of interval-valued fuzzy sets to provide additional freedom or flexibility to stakeholders when making decisions related to watershed management, and (ii) proposing unique integration of three models namely PTMApp, HSPF-SAM and ACPF to achieve watershed planning and management objectives in a cost-effective manner. Although study includes watershed experts from Indian watersheds, the DSS is flexible and replicable to any other watershed across the globe.